Manufacture of iron and steel



UNITED STATES PATENT OFFICE.

SAMUEL INHYTE, 0F REDHILL, ENGLAND.

MANUFACTURE or IRON AND STEEL.

Specificationof Letters Patent. Patented J 1111 29, 1920,

No Drawing. Aplplioation filed July 24, 1917, Serial No. 182,577. Renewed May 1, 1920.- Serial No. 378,260. I

To all whom it may concern:

Be it known that I SAMUEL WHYTE, B. Sc., a subject of the King of Great Britain and Ireland, and residing at 41 Woodlands road, Redhill, in the county of Surrey, England, have invented certain new and useful Improvements Relating to the Manufacture of Iron and Steel, of which the following is a specification.

This invention relates to a new or "improved method of eliminating silica to produce an iron low in silicon.

The present invention does not deal with the purification of iron or steel from sulfur, phosphorus or the like, but only with the elimination of silicon and the production of homogeneous white cast irons.

At present many'ores exist from which excellent cast iron could be obtained but that the content of silicon would be too high for any but special uses, and as no industrial method exists whereby the silicon can be eliminated readily at a low temperature they are not directly available.

The present invention provides this missing step and enables such ores to be used for the direct production of silicon-free cast iron. Further, the processfor eliminating silicon at low temperatures provides a ready means for obtaining cast iron of any desired definite composition. from low grade irons.

The invention consists in eliminating silicon as required from a cast iron contain ing various proportions thereof by heating to a suitable temperature with borax or materials' producing borax, together with free carbon, preferably in the form of graphite. In carrying this invention into effect as applied to the production of a white iron' low in silicon, I take a quantity of gray cast ironand melt it under borax or, after melting, tap it out into a crucible, preferably one in which theheat can be maintained, a layer of borax being melted on the surface of the metal. The crucible is of graphite, or

carbon, preferably in the form of graphite,

is added to the borax or to the bath. I prefer to' force a current of air through the iron, for instance by means of a suitable re? fractory tube. I By this treatment the silicon is more or treatment the metal is cast in the usual Way.

depending on the time of treatment. After WVhen carried to its extreme and the silicon had been eliminated in one test, the iron carbon eutectic was found to have a constant carbon content of about 2.7 per cent.

This white cast iron may be advantageously used as a convenient means of adding carbon in the manufacture of steel.

An improved cast iron with a silicon content according to requirements can also be obtained by partial elimination of silicon in the way just described from a high silicon V I claim as new and desire to secure by Let' ters Patent is 1. A process for the elimination of silicon as required from east irons by heating the iron to a suitable temperature with borax or materials producing borax together with carbon, preferably in the form of graphite,

with or without the introduction of air, substantially' as described.

2. The process of eliminating silicon from cast iron which consists in heating the iron and treating the heatedmetal with alkaline borate in the presence of carbon.

3. The process of eliminating silicon from cast iron which consists in melting the iron,

treating the molten metal with alkaline borate in the presence of carbon and subjecting the molten mass to a current of air.

4. The process .ofeliminatin silicon from cast iron which consists in me ting the iron and adding thereto borax and carbon.

,5. The process of producing. white cast iron which consists in melting cast iron and treating the same with borax and carbon.

6. White cast iron of eutectic composition, containing substantially 2.7% of carbon and substantially free from silicon.

In testimony whereof I have signed my name to this specification I SAMUEL WHYTE. 

